Shawn CalendinehydroGEOPHYSICS Inc.

An Overview of Electric Leak Detection & Leak Location

Methodson Geosynthetic Liners

October 30 – November 1, 2017Hyatt Regency San Antonio Riverwalk

We use electrical geophysical methods to create visual interpretations of the surface and subsurface of the earth.

Succinctly, we see geophysics as a tool for any industry working directly with the earths surface and subsurface. We work with environmental, engineering, ground water,

mining, oil & gas, and chemical industries.

Geophysics

• Water Puddle - ASTM D7002• Water Lance - ASTM D7703• Spark Testing - ASTM D7240 • Arc Testing - ASTM D7953

Liner Leak Location Methods

Water Covered & Soil Covered

ASTM D7007

Bare Liner

A Fact to live with

The Truth About Leakage –All liners leak…

…eventuallyLiner Integrity depends on construction quality and

maintenance through end of life.

A Story You Know!

Unlined ponds leached Chromium-6 into the groundwater causing cancer and autoimmune disease.

Leakage occurred between 1952 – 1966

From 1996 to 2008 settlement costs reached $448 Million

Cleanup cost $700 Million.

Total cost is upwards of $1.1 billion and counting.

Groundwater Contamination In Hinkley, CA

Electric leak location is governed by:

• The inverse relationship between the conductive nature of boundary materials and the highly resistive nature of most geosynthetics.

A hole:

• Breaches the liners resistive nature• Creates a local region of high conductivity

Therefore:

• The electric potential relative to a hole in the liner is significant and measurable

• Current levels remain low and uniform across intact and undamaged liner.

Electrical Leak Detection Basics

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Single Liner

Double Liner

Survey Setup

Transmitter

Receiver

Transmitter &

Transmitting Electrode

Setup

Transmitter Setup

Challenges With Leak location

Challenges with leak location surveys fall into two main categories

• Human Error

• Equipment Limitations

Human Error

Boundary Conditions

Operators must consider:

• All the elements in contact with the margins of the geosynthetics in a lined system

• How well the substrates below and above the liner can carry current

• The quality of electrical isolation in the area to be surveyed

• Geometry not considered.

• Maximum distance between survey lines determined incorrectly

• Lack of routine following sensitivity test throughout survey

• Survey electrical array set up incorrectly - liners have caught on fire from improper transmitter setup

• Suspected leaks marked incorrectly

Human Error

Transmitter

Receiver

Human Error

Geometry Matters…

Exhaustion & Complacency During Physical Data Acquisition

Human Error

Equipment Limitations

Low Level Automation

Contemporary leak location equipment for covered systems is typically divided into two separate components:

A current injector (transmitter) A current detector (receiver).

This lack of connectivity means that system checks are operator-dependent rather than system-dependent.

Survey Area Limitations

Fluid depths need to be lowered to levels that an operator can operate in easily.

Total survey area is reduced to the water level of the pond.

Equipment Limitations

Survey Area Limitations

For material covered liners in mining, leak location equipment is limited by the depth of the material.

The injected current will decrease with increasing depth -at some depth the resulting signal cannot be distinguished from background noise.

Equipment Limitations

Resolution in Conductive Substrates

• Conventional leak location systems break down in highly conductive solutions or substrates.

• Current leaking through a hole is attenuated to such an extent that the signal falls below the detector’s ability to resolve it.

Signal Shadowing

• It is extremely difficult to resolve smaller holes in close proximity to larger ones.

• Large tears or punctures creates a much larger signal pathway. High current flow floods the immediate area, shadowing or obscuring the location of smaller holes nearby.

Equipment Limitations

1) Equipment that houses both the transmitter and receivers in a single system. While transmitting and receiving electrodes are in the pond the actual transmitting, receiving, and data logging occurs in a single device.

2) Numerous independent sensors at discrete intervals in the pond.

3) Data is collected and stored for analysis –

reduces subjectivity and increases objectivity.

4) Hardware has checks and balances to assure system is functioning properly

5) Highly trained personnel

6) Color contoured maps

7) Large patches

The Future of Electric Leak Location

Color Contoured Maps

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Excel Data Analysis

Color Contoured Maps

Slide Number 1Slide Number 2Slide Number 3A Fact to live withA Story You Know!Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29The Future of Electric Leak LocationColor Contoured MapsSlide Number 32Color Contoured Maps